The objectives of this project are to develop a feasible approach to screening for colorectal cancer by fecal occult blood testing at home. This would select a small group of standard risk patients for further aggressive diagnostic studies. Our goals are to evaluate patient compliance, rate of positive screening tests, true postivity, and false-positivity of screening tests of neoplasia, false-negativity, sensitivity, and specificity for diagnostic tests, pathology and staging of neoplastic lesions, survival of patients with detected cancers, mortality in screened and control groups, and cost analysis. A final computer analysis has now been made of the overall results of the first and second examination cycles and is being completed for the third examination cycle representing over 25,000 examinations in 48 months. Detected cancers in the screened group have had a favorable pathologic staging. The Hemoccult II slide has been more sensitive than the single Hemoccult slide but rehydration when added to the HO II slide has resulted in a higher rate of false-positivity. A compliance study of a representative sample of the population is now being completed and will be analyzed in the last quarter of this year. Results of rescreening are currently being evaluated and will be completed in the last quarter of this year. A cost-analysis will follow complete analysis of the three screening cycles. The major thrust for the coming year will be in the followup of all patients. This will be a major effort necessary for evaluation of interval cancers, survival of patients with detected cancers, and mortality in the screened and control populations.